Species with keel-like slit band on the circumference.

Anatoma Woodward, 1859
Type Species (M): Scissurella crispata Fleming, 1828: 385, pi. 6, fig. 3.

Diagnosis
Shell 1-11 mm, trochoid biconical, protoconch with smooth or flocculant sculpture; slit at periphery of whorl, open. Flocculant sculpture characterized by small islands of shell material arranged in an overdispersed pattern; although the islands may occasionally touch one another, adjacent islands do not enclose a discrete area, and the width of the islands along their axis varies by a factor of at least three. More comprehensive diagnoses and discussions have been provided elsewhere (Geiger 2003, 2006b; Geiger & Jansen 2004a).

Description. Shell turbinate, umbilicate; spire elevated. Selenizone at the periphery, slit open one-fifth circumference of last whorl. Sculpture cancellate; protoconch smooth.
Remarks. Species occur in all oceans, primarily offshore on soft bottoms. The type species has the largest sized shell in the family. The genus Scissurella d'Orbigny, 1824, which is unknown in the eastern Pacific, differs in having the selenizone positioned on the shoulder, a lower spire, and a protoconch with axial sculpture.